Adjustable desk lamp



FIG. 1 is a front elevational view of a lighting device according to the new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a perspective view thereof with the lamp heads in a first position;

FIG. 8 is a perspective view thereof with the lamp heads in a second position; and,

FIG. 9 is a perspective view thereof with the lamp heads in a third position. 

The ornamental design for a adjustable desk lamp, as shown and described. 